Distribution Characteristic Analysis and Releasing Risk Assessment of Nutrients in Sediment-Water Interface at Outlet of the Nansi Lake
In order to solve the problem of lack of scientific basis for controlling the risk of nutrient release such as pho-sphate,ammonia nitrogen(NH4-N)and nitrate nitrogen(NO3-N)in sediment-water interface at outlet of the Nansi Lake,China,the vertical profile distribution characteristics and release risks of nutrients in sediment-water interface of outlet of the Nansi Lake were analyzed using diffusion gradients in thin-films and high-resolution dialysis technique.Based on the concentrations of labile phosphorus(DGT-P),labile NH4-N and labile NO3--N,the net diffusion fluxes of the three were calculated and the release risks of the three were assessed.The results show that the concentration of soluble phosphate in overlying water at the outlet of the Nansi Lake is lower than that in pore water,indicating that soluble pho-sphate in sediment may diffuse upward to overlying water due to the concentration gradient.Based on sequential extract methods,calcium-bound phosphorus is the main occurrence form of phosphorus in the sediments at the outlet of the Nansi Lake,and the content of unstable phosphorus in the surface sediments is higher than that in the deep sediments.DGT-P is positively correlated with labile iron,indicating that the release of DGT-P from the sediment-water interface at the outlet of the Nansi Lake is affected by the reduction of iron oxides.The net diffusion fluxes of DGT-P,labile NH4+-N and labile N0,-N at the outlet of Nansi Lake are 17.58,1.16,-40.72 ng/(cm2·d),respectively,indicating that DGT-P and labile NH4-N at the outlet of Nansi Lake are released from sediments to the overlying water and have potential release risks.
environmental sciencenet diffusion fluxdiffusion gradients in thin-filmsnutrientsediment-water inter-facethe Nansi Lake
NETL
NSTL
万方数据
维普
